Patient interface comprising a gas washout vent

ABSTRACT

A gas washout vent for a patient interface may be configured to allow a flow of patient exhaled gas to an exterior of the patient interface to minimise rebreathing of exhaled gas by the patient and the vent may include: a plurality of vent passages extending between a first and a second side of the vent, each vent passage may include: a plurality of first openings extending from the first side towards the second side, said first openings being uniform in size and shape; a plurality of second openings extending from the second side towards the first side, said second openings being uniform in size and shape; and wherein the first openings and the second openings partially overlap each other at an interface to form constricted passages therebetween.

1 CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/546,793, filed Jul. 27, 2017, now allowed, which is the U.S. nationalphase of International Application No. PCT/AU2016/050045, filed Jan. 29,2016, which designated the U.S. and claims the benefit of U.S.Provisional Application No. 62/263,278, filed Dec. 4, 2015, andAustralian Provisional Application No. 2015900281, filed on Jan. 30,2015, the entire contents of each of which are incorporated herein byreference.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in Patent Office patent files orrecords, but otherwise reserves all copyright rights whatsoever.

2 BACKGROUND OF THE TECHNOLOGY 2.1 Field of the Technology

The present technology relates to one or more of the detection,diagnosis, treatment, prevention and amelioration of respiratory-relateddisorders. The present technology also relates to medical devices orapparatus, and their use.

2.2 Description of the Related Art 2.2.1 Human Respiratory System andIts Disorders

The respiratory system of the body facilitates gas exchange. The noseand mouth form the entrance to the airways of a patient.

The airways include a series of branching tubes, which become narrower,shorter and more numerous as they penetrate deeper into the lung. Theprime function of the lung is gas exchange, allowing oxygen to move fromthe air into the venous blood and carbon dioxide to move out. Thetrachea divides into right and left main bronchi, which further divideeventually into terminal bronchioles. The bronchi make up the conductingairways, and do not take part in gas exchange. Further divisions of theairways lead to the respiratory bronchioles, and eventually to thealveoli. The alveolated region of the lung is where the gas exchangetakes place, and is referred to as the respiratory zone. See“Respiratory Physiology”, by John B. West, Lippincott Williams &Wilkins, 9th edition published 2011.

A range of respiratory disorders exist. Certain disorders may becharacterised by particular events, e.g. apneas, hypopneas, andhyperpneas.

Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing(SDB), is characterized by events including occlusion or obstruction ofthe upper air passage during sleep. It results from a combination of anabnormally small upper airway and the normal loss of muscle tone in theregion of the tongue, soft palate and posterior oropharyngeal wallduring sleep. The condition causes the affected patient to stopbreathing for periods typically of 30 to 120 seconds in duration,sometimes 200 to 300 times per night. It often causes excessive daytimesomnolence, and it may cause cardiovascular disease and brain damage.The syndrome is a common disorder, particularly in middle agedoverweight males, although a person affected may have no awareness ofthe problem. See U.S. Pat. No. 4,944,310 (Sullivan).

Cheyne-Stokes Respiration (CSR), Obesity Hyperventilation Syndrome(OHS), Chronic Obstructive Pulmonary Disease (COPD), NeuromuscularDisease (NMD), and Chest wall disorders are examples of respiratorydisorders or disorders that have relationships thereto.

A range of therapies have been used to treat or ameliorate suchconditions. Furthermore, otherwise healthy individuals may takeadvantage of such therapies to prevent respiratory disorders fromarising. However, these have a number of shortcomings.

2.2.2 Therapy

Continuous Positive Airway Pressure (CPAP) therapy has been used totreat Obstructive Sleep Apnea (OSA). The mechanism of action is thatcontinuous positive airway pressure acts as a pneumatic splint and mayprevent upper airway occlusion, such as by pushing the soft palate andtongue forward and away from the posterior oropharyngeal wall. Treatmentof OSA by CPAP therapy may be voluntary, and hence patients may electnot to comply with therapy if they find devices used to provide suchtherapy one or more of: uncomfortable, difficult to use, expensive andaesthetically unappealing.

Non-invasive ventilation (NIV) provides ventilatory support to a patientthrough the upper airways to assist the patient breathing and/ormaintain adequate oxygen levels in the body by doing some or all of thework of breathing. The ventilatory support is provided via anon-invasive patient interface. NIV has been used to treat CSR, OHS,COPD, MD and Chest Wall disorders. In some forms, the comfort andeffectiveness of these therapies may be improved.

Invasive ventilation (IV) provides ventilatory support to patients thatare no longer able to effectively breathe themselves and may be providedusing a tracheostomy tube. In some forms, the comfort and effectivenessof these therapies may be improved.

2.2.3 Treatment Systems

These therapies may be provided by a treatment system or device. Suchsystems and devices may also be used to diagnose a condition withouttreating it.

A treatment system may comprise a Respiratory Pressure Therapy Device(RPT device), an air circuit, a humidifier, a patient interface, anddata management.

Another form of treatment system is a mandibular repositioning device.

2.2.3.1 Patient Interface

A patient interface may be used to interface respiratory equipment toits wearer, for example by providing a flow of air to an entrance to theairways. The flow of air may be provided via a mask to the nose and/ormouth, a tube to the mouth or a tracheostomy tube to the trachea of apatient. Depending upon the therapy to be applied, the patient interfacemay form a seal, e.g., with a region of the patient's face, tofacilitate the delivery of gas at a pressure at sufficient variance withambient pressure to effect therapy, e.g., at a positive pressure ofabout 10 cmH₂O relative to ambient pressure. For other forms of therapy,such as the delivery of oxygen, the patient interface may not include aseal sufficient to facilitate delivery to the airways of a supply of gasat a positive pressure of about 10 cmH₂O.

The design of a patient interface presents a number of challenges. Theface has a complex three-dimensional shape. The size and shape of nosesvaries considerably between individuals. Since the head includes bone,cartilage and soft tissue, different regions of the face responddifferently to mechanical forces. The jaw or mandible may move relativeto other bones of the skull. The whole head may move during the courseof a period of respiratory therapy.

As a consequence of these challenges, some masks suffer from being oneor more of obtrusive, aesthetically undesirable, costly, poorly fitting,difficult to use, and uncomfortable especially when worn for longperiods of time or when a patient is unfamiliar with a system. Forexample, masks designed solely for aviators, masks designed as part ofpersonal protection equipment (e.g. filter masks), SCUBA masks, or forthe administration of anaesthetics may be tolerable for their originalapplication, but nevertheless such masks may be undesirablyuncomfortable to be worn for extended periods of time, e.g., severalhours. This discomfort may lead to a reduction in patient compliancewith therapy. This is even more so if the mask is to be worn duringsleep.

CPAP therapy is highly effective to treat certain respiratory disorders,provided patients comply with therapy. If a mask is uncomfortable, ordifficult to use a patient may not comply with therapy. Since it isoften recommended that a patient regularly wash their mask, if a mask isdifficult to clean (e.g., difficult to assemble or disassemble),patients may not clean their mask and this may impact on patientcompliance.

While a mask for other applications (e.g. aviators) may not be suitablefor use in treating sleep disordered breathing, a mask designed for usein treating sleep disordered breathing may be suitable for otherapplications.

For these reasons, patient interfaces for delivery of CPAP during sleepform a distinct field.

2.2.3.1.1 Seal-Forming Portion

Patient interfaces may include a seal-forming portion. Since it is indirect contact with the patient's face, the shape and configuration ofthe seal-forming portion can have a direct impact the effectiveness andcomfort of the patient interface.

A patient interface may be partly characterised according to the designintent of where the seal-forming portion is to engage with the face inuse. In one form of patient interface, a seal-forming portion maycomprise two sub-portions to engage with respective left and rightnares. In one form of patient interface, a seal-forming portion maycomprise a single element that surrounds both nares in use. Such singleelement may be designed to for example overlay an upper lip region and anasal bridge region of a face. In one form of patient interface aseal-forming portion may comprise an element that surrounds a mouthregion in use, e.g. by forming a seal on a lower lip region of a face.In one form of patient interface, a seal-forming portion may comprise asingle element that surrounds both nares and a mouth region in use.These different types of patient interfaces may be known by a variety ofnames by their manufacturer including nasal masks, full-face masks,nasal pillows, nasal puffs and oro-nasal masks.

A seal-forming portion that may be effective in one region of apatient's face may be inappropriate in another region, e.g. because ofthe different shape, structure, variability and sensitivity regions ofthe patient's face. For example, a seal on swimming goggles thatoverlays a patient's forehead may not be appropriate to use on apatient's nose.

Certain seal-forming portions may be designed for mass manufacture suchthat one design fit and be comfortable and effective for a wide range ofdifferent face shapes and sizes. To the extent to which there is amismatch between the shape of the patient's face, and the seal-formingportion of the mass-manufactured patient interface, one or both mustadapt in order for a seal to form.

One type of seal-forming portion extends around the periphery of thepatient interface, and is intended to seal against the patient's facewhen force is applied to the patient interface with the seal-formingportion in confronting engagement with the patient's face. Theseal-forming portion may include an air or fluid filled cushion, or amoulded or formed surface of a resilient seal element made of anelastomer such as a rubber. With this type of seal-forming portion, ifthe fit is not adequate, there will be gaps between the seal-formingportion and the face, and additional force will be required to force thepatient interface against the face in order to achieve a seal.

Another type of seal-forming portion incorporates a flap seal of thinmaterial positioned about the periphery of the mask so as to provide aself-sealing action against the face of the patient when positivepressure is applied within the mask Like the previous style of sealforming portion, if the match between the face and the mask is not good,additional force may be required to achieve a seal, or the mask mayleak. Furthermore, if the shape of the seal-forming portion does notmatch that of the patient, it may crease or buckle in use, giving riseto leaks.

Another type of seal-forming portion may comprise a friction-fitelement, e.g. for insertion into a naris, however some patients findthese uncomfortable.

Another form of seal-forming portion may use adhesive to achieve a seal.Some patients may find it inconvenient to constantly apply and remove anadhesive to their face.

A range of patient interface seal-forming portion technologies aredisclosed in the following patent applications, assigned to ResMedLimited: WO 1998/004,310; WO 2006/074,513; WO 2010/135,785.

One form of nasal pillow is found in the Adam Circuit manufactured byPuritan Bennett. Another nasal pillow, or nasal puff is the subject ofU.S. Pat. No. 4,782,832 (Trimble et al.), assigned to Puritan-BennettCorporation.

ResMed Limited has manufactured the following products that incorporatenasal pillows: SWIFT™ nasal pillows mask, SWIFT™ II nasal pillows mask,SWIFT™ LT nasal pillows mask, SWIFT™ FX nasal pillows mask and MIRAGELIBERTY™ full-face mask. The following patent applications, assigned toResMed Limited, describe examples of nasal pillows masks: InternationalPatent Application WO2004/073,778 (describing amongst other thingsaspects of the ResMed Limited SWIFT™ nasal pillows), US PatentApplication 2009/0044808 (describing amongst other things aspects of theResMed Limited SWIFT™ LT nasal pillows); International PatentApplications WO 2005/063,328 and WO 2006/130,903 (describing amongstother things aspects of the ResMed Limited MIRAGE LIBERTY™ full-facemask); International Patent Application WO 2009/052,560 (describingamongst other things aspects of the ResMed Limited SWIFT™ FX nasalpillows).

2.2.3.1.2 Positioning and Stabilising

A seal-forming portion of a patient interface used for positive airpressure therapy is subject to the corresponding force of the airpressure to disrupt a seal. Thus a variety of techniques have been usedto position the seal-forming portion, and to maintain it in sealingrelation with the appropriate portion of the face.

One technique is the use of adhesives. See for example US PatentApplication Publication No. US 2010/0000534. However, the use ofadhesives may be uncomfortable for some.

Another technique is the use of one or more straps and/or stabilisingharnesses. Many such harnesses suffer from being one or more ofill-fitting, bulky, uncomfortable and awkward to use.

2.2.3.1.3 Vent Technologies

Some forms of patient interface systems may include a vent to allow thewashout of exhaled carbon dioxide. The vent may allow a flow of gas froman interior space of the patient interface, e.g., the plenum chamber, toan exterior of the patient interface, e.g., to ambient. The vent maycomprise an orifice and gas may flow through the orifice in use of themask. Many such vents are noisy. Others may become blocked in use andthus provide insufficient washout. Some vents may be disruptive of thesleep of a bed-partner 1100 of the patient 1000, e.g. through noise orfocussed airflow.

ResMed Limited has developed a number of improved mask venttechnologies. See International Patent Application Publication No. WO1998/034,665; International Patent Application Publication No. WO2000/078,381; U.S. Pat. No. 6,581,594; US Patent Application PublicationNo. US 2009/0050156; US Patent Application Publication No. 2009/0044808.

Table of noise of prior masks (ISO 17510-2:2007, 10 cmH₂O pressure at 1m)

Sound pressure values of a variety of objects are listed belowA-weighted A-weighted sound power sound pressure level dB(A) dB(A) YearMask name Mask type (uncertainty) (uncertainty) (approx.) Glue-on (*)nasal 50.9 42.9 1981 ResCare nasal 31.5 23.5 1993 standard (*) ResMednasal 29.5 21.5 1998 Mirage ™ (*) ResMed nasal 36 (3) 28 (3) 2000UltraMirage ™ ResMed nasal 32 (3) 24 (3) 2002 Mirage Activa ™ ResMednasal 30 (3) 22 (3) 2008 Mirage Micro ™ ResMed nasal 29 (3) 22 (3) 2008Mirage ™ SoftGel ResMed nasal 26 (3) 18 (3) 2010 Mirage ™ FX ResMednasal 37   29   2004 Mirage Swift ™ pillows (*) ResMed nasal 28 (3) 20(3) 2005 Mirage Swift ™ pillows II ResMed nasal 25 (3) 17 (3) 2008Mirage Swift ™ pillows LT ResMed AirFit nasal 21 (3) 13 (3) 2014 P10pillows (* one specimen only, measured using test method specified inISO3744 in CPAP mode at 10 cmH₂O)

A-weighted sound Object pressure dB(A) Notes Vacuum cleaner: Nilfisk 68ISO3744 at 1 m Walter Broadly Litter Hog: distance B+ GradeConversational speech 60 1 m distance Average home 50 Quiet library 40Quiet bedroom at night 30 Background in TV studio 20

A plurality of smaller vent holes may result in quieter and more diffusevent flow in comparison to large vent holes. Generally, small vent holesare formed by moulding them around a plurality of thin pins as part of amoulding tool. However, thin pins usually result in breakage followingprolonged use and therefore affect the reliability and robustness of thetool. Thus there is a need to produce smaller vent holes more reliably.Moreover, small vent holes may lead to blockage by water droplets formedin the vent holes under for example humidified respiratory pressuretherapy. Thus, there is also a need to reduce the risk of this form ofblockage.

2.2.3.2 Respiratory Pressure Therapy (RPT) Device

Air pressure generators are known in a range of applications, e.g.industrial-scale ventilation systems. However, air pressure generatorsfor medical applications have particular requirements not fulfilled bymore generalised air pressure generators, such as the reliability, sizeand weight requirements of medical devices. In addition, even devicesdesigned for medical treatment may suffer from shortcomings, pertainingto one or more of: comfort, noise, ease of use, efficacy, size, weight,manufacturability, cost, and reliability.

An example of the special requirements of certain RPT devices isacoustic noise.

Table of noise output levels of prior RPT devices (one specimen only,measured using test method specified in ISO3744 in CPAP mode at 10cmH₂O).

A-weighted sound power Year RPT Device name level dB(A) (approx.)C-Series Tango ™ 31.9 2007 C-Series Tango ™ 33.1 2007 with Humidifier S8Escape ™ II 30.5 2005 S8 Escape ™ II 31.1 2005 with H4i ™ Humidifier S9AutoSet ™ 26.5 2010 S9 AutoSet ™ 28.6 2010 with H5i Humidifier

One known RPT device used for treating sleep disordered breathing is theS9 Sleep Therapy System, manufactured by ResMed Limited. Another exampleof an RPT device is a ventilator. Ventilators such as the ResMedStellar™ Series of Adult and Paediatric Ventilators may provide supportfor invasive and non-invasive non-dependent ventilation for a range ofpatients for treating a number of conditions such as but not limited toNMD, OHS and COPD.

The ResMed Elisée™ 150 ventilator and ResMed VS III™ ventilator mayprovide support for invasive and non-invasive dependent ventilationsuitable for adult or paediatric patients for treating a number ofconditions. These ventilators provide volumetric and barometricventilation modes with a single or double limb circuit. RPT devicestypically comprise a pressure generator, such as a motor-driven bloweror a compressed gas reservoir, and are configured to supply a flow ofair to the airway of a patient. In some cases, the flow of air may besupplied to the airway of the patient at positive pressure. The outletof the RPT device is connected via an air circuit to a patient interfacesuch as those described above.

The designer of a device may be presented with an infinite number ofchoices to make. Design criteria often conflict, meaning that certaindesign choices are far from routine or inevitable. Furthermore, thecomfort and efficacy of certain aspects may be highly sensitive tosmall, subtle changes in one or more parameters.

2.2.3.3 Humidifier

Delivery of a flow of air without humidification may cause drying ofairways. The use of a humidifier with an RPT device and the patientinterface produces humidified gas that minimizes drying of the nasalmucosa and increases patient airway comfort. In addition in coolerclimates, warm air applied generally to the face area in and about thepatient interface is more comfortable than cold air. A range ofartificial humidification devices and systems are known, however theymay not fulfil the specialised requirements of a medical humidifier.

Medical humidifiers are used to increase humidity and/or temperature ofthe flow of air in relation to ambient air when required, typicallywhere the patient may be asleep or resting (e.g. at a hospital). Amedical humidifier for bedside placement may be small. A medicalhumidifier may be configured to only humidify and/or heat the flow ofair delivered to the patient without humidifying and/or heating thepatient's surroundings. Room-based systems (e.g. a sauna, an airconditioner, or an evaporative cooler), for example, may also humidifyair that is breathed in by the patient, however those systems would alsohumidify and/or heat the entire room, which may cause discomfort to theoccupants. Furthermore medical humidifiers may have more stringentsafety constraints than industrial humidifiers

While a number of medical humidifiers are known, they can suffer fromone or more shortcomings. Some medical humidifiers may provideinadequate humidification, some are difficult or inconvenient to use bypatients.

3 BRIEF SUMMARY OF THE TECHNOLOGY

The present technology is directed towards providing medical devicesused in the diagnosis, amelioration, treatment, or prevention ofrespiratory disorders having one or more of improved comfort, cost,efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to apparatus used inthe diagnosis, amelioration, treatment or prevention of a respiratorydisorder.

Another aspect of the present technology relates to methods used in thediagnosis, amelioration, treatment or prevention of a respiratorydisorder.

An aspect of certain forms of the present technology is to providemethods and/or apparatus that improve the compliance of patients withrespiratory therapy.

One form of the present technology comprises a gas washout vent for apatient interface, the vent configured to allow a flow of patientexhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient, said vent comprising aplurality of vent passages extending between a first and second side ofthe vent. Each vent passage comprises a first opening extending from thefirst side towards the second side, and a second opening extending fromthe second side towards the first side, wherein the first and secondopenings only partially overlap each other along a plane to form aconstricted passages therebetween. The plane may run through theconstricted passages at the point where the first openings partiallyoverlaps with the second openings and wherein the openings connect atthe constricted passage to form the vent passage extending between thefirst and second sides. The vent may have a vertical axis runningthrough the first and second sides and the plane may be perpendicular tothe vertical axis running in between the first and second sides.Alternatively, the plane may be curved. The plane may be curved tocorrespond to the curvature of the patient interface. For example, thevent may be formed in the shell of the patient interface and the planemay be curved to correspond to the curvature of the shell. The plane mayrun through all the constricted passages. The first and second openingsmay extend towards each other but terminate at the plane. Small ventholes in traditional vents may become blocked by water droplets formingon the walls of the vent holes and blocking vent flow. In this form ofthe present technology, the constricted passage may be formed between atleast one wall of the first opening and at least one wall of the secondopening, wherein the at least one wall of the first opening extends froma first side of the plan towards the first side of the vent and the atleast one wall of the second opening extends from a second side of theplane towards the second side of the vent. Thus, the constricted passagemay be formed between at least two walls on different sides of a plane.This configuration may reduce the ability for water droplets to formbetween the walls of the constricted passage thereby reducing the riskof blockage under humidification. The partial overlap between the firstand second openings also allows for the constricted passage to be formedfrom larger openings. The constricted passage forms a smaller passagewayfor the flow of exhaled air between the first and second openings,thereby constricted vent flow for noise muffling and increaseddiffuseness. The exhaled gases from the patient may flow through thelarger first openings, through the constricted passage and into thesecond openings before exiting the gas washout vent and into theatmosphere. Additionally, each first opening may overlap a plurality ofsecond openings to form a plurality of constricted passages. Forexample, each first opening may partially overlap four second openingsto form four separate constricted passages. Thus, the flow of exhaledgas may flow into a single first opening then divide through a pluralityof constricted passages, for example through four constricted passages,before flowing into a plurality of partially overlapping second openingsto exit the gas washout vent. In this instance the vent flow of exhaledair may divide into a plurality of constricted flow paths for noisemuffling and added diffuseness.

Another aspect of one form of the present technology is the gas washoutvent for a patient interface, the vent configured to allow a flow ofpatient exhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient, said vent comprising aplurality of vent passages formed by a wall extending between a firstand second side of the vent. Each vent passage comprises a first openingformed by the wall extending from the first side towards the secondside, and a second opening formed by the wall extending from the secondside towards the first side, wherein the wall transitions between thefirst opening to the second opening by a stepped cross section to form aconstricted passage therebetween.

Another aspect of one form of the present technology is the gas washoutvent, wherein the first and/or second openings have a substantiallyconstant cross sectional area that is larger than a cross sectional areaof the constricted passage. The cross sectional area of the first and/orsecond openings may be modified to alter the vent flow noisecharacteristics and diffuseness of the flow of exhaled gas through thefirst openings. A constant cross sectional area may provide desiredsubstantially constant flow characteristics through the first and/orsecond openings. Having a substantially constant cross sectional area ofthe first opening may also assist in ease of manufacturability whenmoulding the openings using a moulding tool with pins having asubstantially constant cross sectional area. For example, the firstopenings may be substantially cylindrical, cube or cuboid in shape.Alternatively, the substantially constant cross sectional area may beformed by at least one curved wall. The at least one wall of the firstand second openings may direct the flow of exhaled gases in manner toreduce noise and increase diffuseness. The constant cross sectional areaof each first or second opening may be between 0.3 to 1 mm2. This crosssectional area allows for the openings to be moulded using a mouldingtool having pins of a sufficient thickness to ensure durability andreliability upon prolonged repeated use. Preferably, the constant crosssectional area of the first or second opening may be 0.5 mm2. The crosssectional area of the constricted passage may be between 0.05 to 0.2mm2. Preferably the cross sectional area of the constricted passage maybe 0.1 mm2. In traditional smaller hole vents, blockage may occur underhumidification as water droplets on the walls forming the vent holes andblock the vent flow. The constricted passage formed by the partiallyoverlapping first and second openings reduces the risk of blockage asthe constricted passage is formed between first and second openingshaving a larger cross sectional area than the constricted passage. Forexample, having a cross sectional area of 0.3 to 1 mm² may besufficiently large enough to prevent blockage under humidification asthe space provided between the walls of the opening may prevent waterdroplets from blocking the opening. Thus, the constricted passage inthis form of the present technology allows for obtaining the benefits ofa smaller hole vent whilst reducing the risk of blockage underhumidification.

Another aspect of one form of the present technology is the gas washoutvent, wherein the first and/or second openings have a varying crosssectional area with a minimum cross sectional area that is larger than across sectional area of the constricted passage. The minimum crosssectional area of each opening may be taken at the narrowest point ofeach opening and compared to the cross sectional area of the constrictedpassage between the first and second openings. The minimum crosssectional area of each opening may be between 0.3 to 1 mm2. Preferably,the minimum cross sectional may be 0.5 mm2. In contrast, the crosssectional area of the constricted passage may be between 0.05 to 0.2mm2. Preferably, the cross sectional area of the constricted passage maybe 0.1 mm2. A varying cross sectional area of the openings may providedesired varying flow characteristics of exhaled gases through the firstand/or second openings. The walls of each opening may be structured toprovide the varying cross sectional such that the flow of exhaled gas isdirected to provide the desired flow characteristics. For example, theopenings may be formed by a curved and/or tilted wall to form thevarying cross sectional area. Alternatively, the varying cross sectionalarea may be formed by a plurality of curved and/or tilted walls. The atleast one wall forming the openings may provide a tortuous flow path forthe flow of exhaled gases flowing through the openings. Moreover, the atleast one wall may be angled to direct the flow in a desiredorientation. Similarly, the walls of the first and/or second openingsmay converge towards the constricted passage. In an alternative example,the first openings may be angled relative to the second openings toprovide the tortuous flow path through the vent. The at least one wallof the first and second openings may direct the flow of exhaled gases inmanner to reduce noise and increase diffuseness.

Another aspect of one form of the present technology is the gas washoutvent, wherein the first and/or second openings are symmetrical, eachhaving a central axis. The plurality of first openings may have parallelcentral axes. The plurality of second openings may also have parallelcentral axes. Each vent hole may comprise a first opening having acentral axis that is angled relative to the central axis of thecorresponding second opening to define a tortuous flow path of exhaledgas through the vent hole. The plurality of first openings may be offsetfrom the plurality of second openings such that the openings partiallyoverlap to form the constricted passage. Alternatively, two or more ofthe plurality of first openings may have a central axis that is angleddifferently to one another to increase the diffuseness of the vent flow.Similarly, two or more of the plurality of second openings may also havea central axis that is angled differently to one another to increase thediffuseness of the vent flow.

Another aspect of one form of the present technology is the gas washoutvent, wherein the first and/or second openings are asymmetrical. Thefirst openings may be offset from the second openings such that theyonly partially overlap to form the constricted passage. The asymmetricalshapes of the openings may decrease noise of the vent flow and/orincrease its diffuseness.

Another aspect of one form of the present technology is the gas washoutvent, wherein the first and second sides are integrally formed. Thefirst and second sides may be moulded into a single piece, having aplurality of first openings on the first side that partially overlapcorresponding second openings on the second side to form a constrictedpassage therebetween. Integrally forming the vent allows for an easy wayto manufacture a vent having smaller vent holes at the constricted ventpassage formed from partially overlapping larger vent openings on eachside of the vent. Alternatively, the first side may be separately formedfrom the second side of the vent. The first side may be permanently orsemi-permanently attached to the second side. In another example, thefirst side may be removably attached to the second side.

Another aspect of one form of the present technology is a patientinterface for sealed delivery of a flow of air at a continuouslypositive pressure with respect to ambient air pressure to an entrance tothe patient's airways including at least entrance of a patient's nares,wherein the patient interface is configured to maintain a therapypressure in a range of about 4 cmH2O to about 30 cmH2O above ambient airpressure in use, throughout the patient's respiratory cycle, while thepatient is sleeping, to ameliorate sleep disordered breathing; saidpatient interface comprising a gas washout vent. The gas washout ventmay be configured to allow a flow of patient exhaled gas to an exteriorof the patient interface to minimise rebreathing of exhaled gas by thepatient. The vent may comprise a plurality of vent passages extendingbetween a first and second side of the vent. Each vent passagecomprising a first opening extending from the first side towards thesecond side and a second opening extending from the second side towardsthe first side. The first and second openings only partially overlapeach other along a plane to form constricted passages therebetween, theplane lying between the first and second sides. The patient interfacemay comprise a shell forming a plenum chamber for the delivery oftherapy pressure to the entrance of the patient's airways. The vent maybe integrally formed with the vent. Alternatively the vent may beremovably attachable to the patient interface. For example, the vent maybe removably attached to the shell of the patient interface. The patientinterface may further comprise a connecting member such as an elbowconnector for fluidly connecting the patient interface to a gas deliveryconduit. The vent may be removably attached or integrally formed withthe connecting member or gas delivery conduit. The vent may beorientated such that the second side of the vent is facing an interioror plenum chamber of the patient interface.

An aspect of one form of the present technology is a method ofmanufacturing a gas washout vent for a patient interface, the ventconfigured to allow a flow of patient exhaled gas to an exterior of thepatient interface to minimise rebreathing of exhaled gas by the patient,said vent comprising a plurality of vent passages extending from a firstside to a second side. The gas washout vent may be manufactured by theprocess comprising the steps of providing a moulding tool comprising afirst plurality of pins to extending from a first side towards a secondside of the tool and a second plurality of pins extending from thesecond side towards the first side. The first plurality of pins and thesecond plurality of pins may slidingly extend towards each other.Alternatively either of the first of pins or the second plurality ofpins may slidingly extend. A cavity is formed around the first andsecond plurality of pins for moulding respective first and secondopenings. The pins are positioned such that the first plurality of pinsengage the second plurality of pins on opposing ends between the firstand second sides of the tool. The first plurality of pins are offsetfrom the second plurality of pins to only partially overlap uponengagement. The first plurality of pins may be axially offset to thesecond plurality of pins according to an axis of symmetry of each pin.Each pin of the first plurality of pins may engage one or more pins ofthe second plurality of pins, such that a constricted vent passage maybe moulded around the point of engagement. All the pins may engage on asingle horizontal plane that runs between the first and second sides ofthe moulding vent. The pins may then be retracted towards opposing sidesto demould the tool from the vent. The first plurality of pins may beoffset from the second plurality of pins such that only a portion of theend of each first plurality of pins engages with only a portion of theend of each second plurality of pins. This engaging portion provides thepartial overlap such that moulding around the engaging ends forms aconstricted passage between the first and second openings. Moulding agas washout vent using this method allows for the moulding of gaswashout vents with smaller vent holes provided by the constrictedpassages without the need for a tool with smaller moulding pins. Theprobability of breakage after short term use is increased when mouldingpins are made smaller and thinner for moulding corresponding small ventholes around the pins. This ultimately reduces the reliability androbustness of the moulding tool for prolonged use. Thus, a moulding toolwith opposing pins on a first and second side may provide a means formoulding smaller vent holes without the need for smaller or thinnerpins. The first and/or second plurality of pins may each have a crosssection area of between 0.3 to 1 mm². The cross sectional area of eachof the first and/or second plurality of pins may be 0.5 mm². The firstplurality of pins may partially overlap the second plurality of pinssuch that they engage across a cross sectional area of between 0.05 to0.2 mm². The partial overlap may form a constricted passage with a crosssectional area of between 0.05 to 0.2 mm². The constricted passage mayhave a cross sectional area of 0.1 mm². Having the first and secondplurality of pins engage in this manner also allows for ease of mouldingvent holes with constricted passages that are or irregular shapes toincrease diffusivity and/or decrease noise by providing a tortuous flowpath for exhaled gases through the vent. The irregularly shaped ventholes may be formed by the first and/or second plurality of pins withirregular shapes. Having the pins engage on opposing sides allows foreasier retraction of the pins towards their respective sides aftermoulding the vent holes.

An aspect of the present technology is directed to a gas washout ventfor a patient interface, the vent configured to allow a flow of patientexhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient. The gas washout vent maycomprise: a plurality of vent passages extending between a first and asecond side of the vent, each vent passage comprising: a plurality offirst openings extending from the first side towards the second side,said first openings being uniform in size and shape; a plurality ofsecond openings extending from the second side towards the first side,said second openings being uniform in size and shape; and wherein thefirst openings and the second openings partially overlap each other atan interface to form constricted passages therebetween.

In examples, (a) the first openings and the second openings mayterminate at the interface to form the constricted passages, (b) theinterface may be curved, (c) the interface may be flat, (d) each of thefirst openings may partially overlap a plurality of the second openings,(e) each of the first openings may have a substantially constant crosssectional area through the first side that is larger than a crosssectional area of the constricted passage, (f) each of the secondopenings may have a substantially constant cross sectional area throughthe second side that is larger than a cross sectional area of theconstricted passage, (g) each of the first openings and each of thesecond openings may be formed by a curved wall, (h) the wall may form acylindrical opening, (i) at least one of the first openings and at leastone of the second openings may have a varying cross sectional area, (j)the varying cross sectional area may have a minimum cross sectional areathat is larger than the cross sectional area of the correspondingconstricted passage, (k) each of the first openings may be formed by atleast a first wall, (l) the first wall may comprise a plurality of firstsides, (m) the plurality of first sides may include at least one tiltedfirst side to form an angled flow path through each of the firstopenings, (n) the plurality of first sides may include at least onecurved first side, (o) each of the second openings may be formed by asecond wall, (p) the second wall may comprise a plurality of secondsides, (q) the plurality of second sides may include at least one tiltedsecond side to form an angled flow path though each of the secondopenings, (r) at least one of the second sides of the second wall of oneof the second openings may be tilted relative to at least one of thesecond sides of the second wall of an adjacent one of the secondopenings such that the flow of exhaled gases exiting one of the secondopenings is directed towards the flow exiting the adjacent one of thesecond openings, (s) the plurality of second sides may include at leastone curved second side, (t) the cross-sectional area of each of thefirst openings may decrease towards the constricted passage, (u) thecross-sectional area of each of the second openings may decrease towardsthe constricted passage, (v) each of the constricted passages has across sectional area between 0.05 mm2 and 0.2 mm2, (w) each of theconstricted passages has a cross sectional area of 0.1 mm2, (x) each ofthe first openings may have a cross sectional area between 0.3 mm2 and 1mm2, (y) each of the first openings may have a cross sectional area of0.5 mm2, (z) each of the second openings may have a cross sectional areabetween 0.3 mm2 and 1 mm2, (aa) each of the second openings may have across sectional area of 0.5 mm2, (bb) an axis may be defined througheach of the first openings and each of the second openings, (cc) eachaxis defined through each of the first openings may be oriented relativeto the interface at a different angle than each axis defined througheach of the second openings, (dd) the axes defined through each of thefirst openings may be parallel, (ee) the axes defined through each ofthe second openings may be parallel, (ee) each of the first openings maybe a cube or a cuboid in shape, (ff) each of the second openings may bea cube or a cuboid in shape, (gg) each of the first openings may beasymmetrical about an axis, (hh) each of the second openings may beasymmetrical about an axis, and/or (ii) the first side and the secondside may be integrally formed.

An aspect of the present technology is directed to a patient interfacefor sealed delivery of a flow of air at a continuously positive pressurewith respect to ambient air pressure to an entrance to the patient'sairways including at least entrance of the patient's nares, wherein thepatient interface is configured to maintain a therapy pressure in arange of about 4 cmH2O to about 30 cmH2O above ambient air pressure inuse, throughout the patient's respiratory cycle, while the patient issleeping, to ameliorate sleep disordered breathing. The patientinterface may comprise: a gas washout vent configured to allow a flow ofpatient exhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient, said vent comprising: aplurality of vent passages extending between a first side and a secondside of the gas washout vent, each vent passage comprising: a firstopening extending from the first side towards the second side and beinguniform in size and shape; a second opening extending from the secondside towards the first side and being uniform in size and shape; andwherein the first openings and the second openings partially overlapeach other along an interface to form constricted passages therebetween.

In examples, (a) the interface may be curved, (b) the interface may beflat, (c) the patient interface may further comprise a plenum chamberthat at least in part defines a breathing chamber of the patientinterface, (d) the gas washout vent may be integrally formed with theplenum chamber, (e) the gas washout vent may be removably attached toplenum chamber, (f) the second side of the gas washout vent may face thebreathing chamber of the patient interface, (g) the patient interfacemay further comprise a connecting member configured to connect thepatient interface to a gas delivery conduit, the gas washout ventprovided to the connecting member, (h) the second side of the gaswashout vent may face an interior of the connecting member, (i) the gaswashout vent may be integrally formed with the connecting member, and/or(j) the gas washout vent may be removably attached to the connectingmember.

An aspect of the present technology is directed to a method ofmanufacturing a gas washout vent for a patient interface, the ventconfigured to allow a flow of patient exhaled gas to an exterior of thepatient interface to minimise rebreathing of exhaled gas by the patient,said vent comprising a plurality of vent passages extending from a firstside to a second side. The method may comprise: providing a mouldingtool comprising: a first plurality of pins extending from a first sidetowards a second side of the tool; a second plurality of pins extendingfrom the second side towards the first side of the tool; and a cavityformed around the first plurality of pins and the second plurality ofpins; wherein the first plurality of pins and the second plurality ofpins extend to engage on opposing ends between the first side and thesecond side such that the first plurality of pins are offset from thesecond plurality of pins to partially overlap upon engagement; andadding molten moulding material to the cavity of the moulding tool suchthat a plurality of first openings and a plurality of second openingsthat are partially overlapping are moulded around the first plurality ofpins and the second plurality of pins to form constricted passagesbetween the first openings and the second openings, the constrictedpassages formed around the engaging ends of the first plurality ofopenings and the second plurality of openings.

In examples, (a) the method may further comprise retracting the firstplurality of pins and/or the second plurality of pins from the mouldingmaterial to demould the vent from the tool, (b) the pins may slidinglyextend towards each other, (c) each of the first plurality of pins mayengage with two or more of the second plurality of pins, (d) the firstplurality of pins may engage with the second plurality of pins onopposing sides of a horizontal plane running through a point ofengagement between the first plurality of pins and the second pluralityof pins, (e) the first plurality of pins may have an axis of symmetrythat is axially offset from an axis of symmetry of the second pluralityof pins, (f) each of the first plurality of pins may have a crosssectional area between 0.3 mm2 and 1 mm2, (g) each of the firstplurality of pins may have a cross sectional area of 0.5 mm2, (h) thefirst plurality of pins may partially overlap the second plurality ofpins to form each of the constricted passages with a cross sectionalarea between 0.05 mm2 and 0.2 mm2, and/or (i) the cross sectional areaof each of the constricted passages may be 0.1 mm2.

An aspect of the present technology is directed to a gas washout ventfor a patient interface, the vent configured to allow a flow of patientexhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient. The vent may comprise: aplurality of layers, wherein each layer comprises a plurality of ventpassages extending between a first side and a second side of each layer,each vent passage comprising: a first opening extending from the firstside towards the second side and being uniform in shape and size; asecond opening extending from the second side towards the first side andbeing uniform in shape and size; and wherein each first opening and eachsecond opening only partially overlap each other along an interface toform constricted passages therebetween.

An aspect of the present technology is directed to a gas washout ventfor a patient interface, the vent configured to allow a flow of patientexhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient. The vent may comprise: aplurality of vent passages extending between a first side and a secondside of the vent, each vent passage comprising: a first openingextending from the first side towards the second side and being uniformin shape and size; a second opening extending from the second sidetowards the first side and being uniform in shape and size; and whereineach first opening is offset from each second opening along an interfaceto form a constricted passage therebetween.

An aspect of the present technology is directed to a gas washout ventfor a patient interface, the vent configured to allow a flow of patientexhaled gas to an exterior of the patient interface to minimiserebreathing of exhaled gas by the patient. The vent may comprise: aplurality of vent passages formed by a wall extending between a firstside and a second side of the vent, each vent passage comprising: afirst opening formed by the wall extending from the first side towardsthe second side and being uniform in shape and size; a second openingformed by the wall extending from the second side towards the first sideand being uniform in shape and size; and wherein the wall transitionsbetween the first opening to the second opening by a stepped crosssection to form a constricted passage therebetween.

An aspect of the present technology is directed to a vent for a patientinterface. The vent may comprise: a first side having a plurality offirst openings defined by a plurality of first walls, said firstopenings being uniform in size and shape; a second side having aplurality of second openings defined by a plurality of second walls,said second openings being uniform in size and shape, wherein the firstside and the second side are positioned adjacent to one another at aninterface region, and wherein each of the first openings overlaps withat least two of the second openings at the interface region and each ofthe second openings overlaps with at least two of the first openings atthe interface region such that a constricted passage is formed at eachoverlap of one of the first openings and one of the second openings.

In examples, (a) each of the first openings may be defined by at leastone side of the first walls and each of the second openings is definedby at least one side of the second walls, (b) each first opening may bedefined by a plurality of sides of the first walls and each secondopening is defined by a plurality of sides of the second walls, (c) eachfirst opening may have a substantially polygonal profile and each secondopening has a substantially polygonal profile, (d) the first walls maybe comprised of a first plurality of ellipsoidal structures and thesecond walls may be comprised of a second plurality of ellipsoidalstructures, (e) the first plurality of ellipsoidal structures may beuniform and overlapping, (f) the second plurality of ellipsoidalstructures may be uniform and overlapping, (g) the first plurality ofellipsoidal structures and the second plurality of ellipsoidalstructures may be identical in shape and size, (h) the first pluralityof ellipsoidal structures and the second plurality of ellipsoidalstructures may be different in shape and size, (i) the sides of each ofthe first walls may be tilted toward one another relative to theinterface region and the sides of each of the second walls may be tiltedtoward one another relative to the interface region, (j) the sides ofeach of the first walls may be tilted in the same direction relative tothe interface region and the sides of each of the second walls may betilted toward one another relative to the interface region, (k) thesides of each of the first walls may be tilted in the same directionrelative to the interface region, the sides of each of the second wallsmay be tilted in the same direction relative to the interface region,and the sides of the first walls and the sides of the second walls maybe tilted in opposite direction relative to one another, (l) each firstopening may be defined by a single side of the first walls such thateach first opening has a profile that is substantially elliptical orsubstantially circular, (m) each second opening may be defined by asingle side of the second walls such that each second opening has aprofile that is substantially elliptical or substantially circular, (n)the first walls and/or the second walls may be curved, (o) each of thefirst openings may overlap with four of the second openings and each ofthe second openings may overlap with four of the first openings, (p) thefirst walls and the second walls may overlap, (q) the first side and thesecond side may be spaced apart at the interface region, (r) the firstside and the second side may be in contact at the interface region, (s)the first side and the second side may comprise a single piece ofhomogeneous material, (t) the first side and the second side maycomprise two separate pieces of homogeneous material that arepermanently attached, (u) the first side and the second side maycomprise two separate pieces of homogeneous material that are releasablyattached, (v) the interface region may be planar such that the firstside and the second side are substantially flat, (w) the interfaceregion may be curved in at least one direction such that the first sideand the second are curved in said at least one direction, (x) the firstopenings may be distributed on the first side in any one of arectangular grid pattern, a circular pattern, a spiral pattern, anelliptical pattern, a square pattern, a polygonal pattern, a series ofrows and columns, and a pattern mirrored about an axis of the firstside, (y) the second openings may be distributed on the second side inany one of a rectangular grid pattern, a circular pattern, a spiralpattern, an elliptical pattern, a square pattern, a polygonal pattern, aseries of rows and columns, and a pattern mirrored about an axis of thesecond side, (z) each constricted passage may define a flow path for theflow of gas through corresponding ones of the first openings andcorresponding ones of the second openings, (aa) the flow path may be anyone of linear, non-linear, and tortuous, (bb) the first openings and thesecond openings may be sized and shaped such that at least two adjacentflow paths cross one another, and/or (cc) a patient interface for sealeddelivery of a flow of air at a continuously positive pressure withrespect to ambient air pressure to an entrance to the patient's airwaysincluding at least the entrance of the patient's nares, wherein thepatient interface is configured to maintain a therapy pressure in arange of about 4 cmH2O to about 30 cmH2O above ambient air pressure inuse, throughout the patient's respiratory cycle, while the patient issleeping, to ameliorate sleep disordered breathing, said patientinterface may comprise: a sealing structure configured to form apneumatic seal around an area surrounding an entrance to the patient'sairways; a positioning and stabilising structure configured to maintainthe sealing structure in sealing contact with the area surrounding anentrance to the patient's airways while maintaining a therapeuticpressure at the entrance to the patient's airways; a plenum chamberconfigured to be pressurised at a pressure above ambient pressure inuse; at least one vent according to any of the above examples, said ventbeing configured to allow a flow of patient exhaled CO2 to an exteriorof the patient interface to minimise rebreathing of exhaled CO2 by thepatient.

An aspect of the present technology is directed to a method ofmanufacturing a vent with a first tool having a first plurality of pinsextending from a first base and a second tool having a second pluralityof pins extending from a second base. The method may comprise: engagingthe first tool and the second tool together such that the firstplurality of pins and the second plurality of pins are in contact withone another at an interface region, the first plurality of pins at leastpartially defining a first plurality of voids and the second pluralityof pins at least partially defining a second plurality of voids; moldingthe vent by filling the first plurality of voids and the secondplurality of voids with a vent material; and disengaging the first tooland the second tool from one another after a predetermined period oftime.

In examples, (a) the first plurality of pins and the second plurality ofpins may be sized and shaped such that when engaged each of the firstplurality of pins overlaps with at least two of the second plurality ofpins and each of the second plurality of pins overlaps with at least twoof the first plurality of pins, (b) each of the first plurality of voidsmay be defined at least in part by the first base, sides of the firstplurality of pins, and a free end surface of one of the second pluralityof pins and each of the second plurality of voids is defined at least inpart by the second base, sides of the second plurality of pins, and afree end surface of one of the first plurality of pins.

Another aspect of one form of the present technology is a patientinterface that is moulded or otherwise constructed with a perimetershape which is complementary to that of an intended wearer.

An aspect of one form of the present technology is a method ofmanufacturing apparatus.

An aspect of one form of the present technology is a portable RPT devicethat may be carried by a person, e.g., around the home of the person.

An aspect of one form of the present technology is a patient interfacethat may be washed in a home of a patient, e.g., in soapy water, withoutrequiring specialised cleaning equipment. An aspect of one form of thepresent technology is a humidifier tank that may be washed in a home ofa patient, e.g., in soapy water, without requiring specialised cleaningequipment.

Of course, portions of the aspects may form sub-aspects of the presenttechnology. Also, various ones of the sub-aspects and/or aspects may becombined in various manners and also constitute additional aspects orsub-aspects of the present technology.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description,abstract, drawings and claims.

4 BRIEF DESCRIPTION OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

4.1 Treatment Systems

FIG. 1A shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a nasal pillows, receiving a supply ofair at positive pressure from an RPT device 4000. Air from the RPTdevice is humidified in a humidifier 5000, and passes along an aircircuit 4170 to the patient 1000. A bed partner 1100 is also shown.

FIG. 1B shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a nasal mask, receiving a supply of airat positive pressure from an RPT device 4000. Air from the RPT device ishumidified in a humidifier 5000, and passes along an air circuit 4170 tothe patient 1000.

FIG. 1C shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a full-face mask, receiving a supply ofair at positive pressure from an RPT device 4000. Air from the RPTdevice is humidified in a humidifier 5000, and passes along an aircircuit 4170 to the patient 1000.

4.2 Respiratory System and Facial Anatomy

FIG. 2A shows an overview of a human respiratory system including thenasal and oral cavities, the larynx, vocal folds, oesophagus, trachea,bronchus, lung, alveolar sacs, heart and diaphragm.

FIG. 2B shows a view of a human upper airway including the nasal cavity,nasal bone, lateral nasal cartilage, greater alar cartilage, nostril,lip superior, lip inferior, larynx, hard palate, soft palate,oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

FIG. 2C is a front view of a face with several features of surfaceanatomy identified including the lip superior, upper vermilion, lowervermilion, lip inferior, mouth width, endocanthion, a nasal ala,nasolabial sulcus and cheilion. Also indicated are the directionssuperior, inferior, radially inward and radially outward.

FIG. 2D is a side view of a head with several features of surfaceanatomy identified including glabella, sellion, pronasale, subnasale,lip superior, lip inferior, supramenton, nasal ridge, alar crest point,otobasion superior and otobasion inferior. Also indicated are thedirections superior & inferior, and anterior & posterior.

FIG. 2E is a further side view of a head. The approximate locations ofthe Frankfort horizontal and nasolabial angle are indicated. The coronalplane is also indicated.

FIG. 2F shows a base view of a nose with several features identifiedincluding naso-labial sulcus, lip inferior, upper Vermilion, naris,subnasale, columella, pronasale, the major axis of a naris and thesagittal plane.

FIG. 2G shows a side view of the superficial features of a nose.

FIG. 2H shows subcutaneal structures of the nose, including lateralcartilage, septum cartilage, greater alar cartilage, lesser alarcartilage, sesamoid cartilage, nasal bone, epidermis, adipose tissue,frontal process of the maxilla and fibrofatty tissue.

FIG. 2I shows a medial dissection of a nose, approximately severalmillimeters from a sagittal plane, amongst other things showing theseptum cartilage and medial crus of greater alar cartilage.

FIG. 2J shows a front view of the bones of a skull including thefrontal, nasal and zygomatic bones. Nasal concha are indicated, as arethe maxilla, and mandible.

FIG. 2K shows a lateral view of a skull with the outline of the surfaceof a head, as well as several muscles. The following bones are shown:frontal, sphenoid, nasal, zygomatic, maxilla, mandible, parietal,temporal and occipital. The mental protuberance is indicated. Thefollowing muscles are shown: digastricus, masseter, sternocleidomastoidand trapezius.

FIG. 2L shows an anterolateral view of a nose.

4.3 Patient Interface

FIG. 3A shows a patient interface in the form of a nasal mask inaccordance with one form of the present technology.

4.4 RPT Device

FIG. 4A shows an RPT device in accordance with one form of the presenttechnology.

FIG. 4B is a schematic diagram of the pneumatic path of an RPT device inaccordance with one form of the present technology. The directions ofupstream and downstream are indicated.

4.5 Humidifier

FIG. 5A shows an isometric view of a humidifier in accordance with oneform of the present technology.

FIG. 5B shows an isometric view of a humidifier in accordance with oneform of the present technology, showing a humidifier reservoir 5110removed from the humidifier reservoir dock 5130.

4.6 Breathing Waveforms

FIG. 6A shows a model typical breath waveform of a person whilesleeping.

4.7 Vent

FIG. 7A shows a first side and second side of a vent in accordance withan example of the present technology.

FIG. 7B shows a detailed perspective view of the first side of the ventshown in FIG. 7A.

FIG. 7C shows the first side of a vent in accordance with an example ofthe present technology and indicates the position of a cross section7D-7D.

FIG. 7D shows a cross sectional view of the vent of FIG. 7C takenthrough line 7D-7D.

FIG. 7E shows a detailed view of the cross sectional view shown in FIG.7D.

FIG. 7F shows another detailed cross-sectional view of the vent shown inFIG. 7C.

FIG. 7G shows a detailed cross sectional view of a curved vent inaccordance with another form of the present technology.

FIG. 7H shows a detailed cross-sectional view of a vent shown inperspective according to another example of the present technology.

FIG. 7I shows a side view of the vent shown in FIG. 7A and indicatescross-section line 7J-7J.

FIG. 7J illustrates the top view of the cross section of the vent shownin FIG. 7I taken through line 7J-7J and shows a detailed view of thesecond side.

FIG. 7K illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 7L illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 7M illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 8A shows perspective view of another form of the present technologyhaving a first side and a second side in separate components.

FIG. 8B shows a cutaway perspective view of the vent of FIG. 8A.

FIG. 8C shows a detailed top view of the first side of the vent of FIG.8A.

FIG. 8D shows a detailed perspective view of the first side of the ventof FIG. 8A.

FIG. 8E shows a detailed cross sectional side view of the vent of FIG.8A wherein the first side and second side are separated.

FIG. 8F illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 8G illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 8H illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 8I illustrates a detailed cross sectional view of a curved vent inaccordance with another form of the present technology.

FIG. 8J illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 9A illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 9B illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 9C illustrates a detailed cross sectional side view of the vent inaccordance with another form of the present technology.

FIG. 10 shows a perspective view of a patient interface comprising avent in accordance with the present technology, the figure illustratinga detailed view of the first side.

FIG. 11A illustrates a moulding tool for moulding a vent in accordancewith the present technology.

FIG. 11B shows a detailed schematic of partially overlapped pins of themoulding tool in accordance with the present technology.

FIG. 11C shows a detailed schematic of partially overlapped pins of themoulding tool shown in FIG. 11A.

FIG. 11D shows a detailed side view of the pins of the moulding toolshown in FIG. 11A.

FIG. 11E shows a detailed side view of the pins of the moulding toolshown in FIG. 11A with moulding material added.

5 DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

Before the present technology is described in further detail, it is tobe understood that the technology is not limited to the particularexamples described herein, which may vary. It is also to be understoodthat the terminology used in this disclosure is for the purpose ofdescribing only the particular examples discussed herein, and is notintended to be limiting.

The following description is provided in relation to various exampleswhich may share one or more common characteristics and/or features. Itis to be understood that one or more features of any one example may becombinable with one or more features of another example or otherexamples. In addition, any single feature or combination of features inany of the examples may constitute a further example.

5.1 Therapy

In one form, the present technology comprises a method for treating arespiratory disorder comprising the step of applying positive pressureto the entrance of the airways of a patient 1000.

In certain examples of the present technology, a supply of air atpositive pressure is provided to the nasal passages of the patient viaone or both nares.

In certain examples of the present technology, mouth breathing islimited, restricted or prevented.

5.2 Treatment Systems

In one form, the present technology comprises an apparatus or device fortreating a respiratory disorder. The apparatus or device may comprise anRPT device 4000 for supplying pressurised air to the patient 1000 via anair circuit 4170 to a patient interface 3000.

5.3 Patient Interface

A non-invasive patient interface 3000 in accordance with one aspect ofthe present technology comprises the following functional aspects: aseal-forming structure 3100, a plenum chamber 3200, a positioning andstabilising structure 3300 and one form of connection port 3600 forconnection to air circuit 4170. In some forms a functional aspect may beprovided by one or more physical components. In some forms, one physicalcomponent may provide one or more functional aspects. In use theseal-forming structure 3100 is arranged to surround an entrance to theairways of the patient so as to facilitate the supply of air at positivepressure to the airways.

5.3.1 Seal-Forming Structure

In one form of the present technology, a seal-forming structure 3100provides a seal-forming surface, and may additionally provide acushioning function.

A seal-forming structure 3100 in accordance with the present technologymay be constructed from a soft, flexible, resilient material such assilicone.

In one form, the seal-forming structure 3100 comprises a sealing flangeand a support flange. The sealing flange comprises a relatively thinmember with a thickness of less than about 1 mm, for example about 0.25mm to about 0.45 mm, that extends around the perimeter of the plenumchamber 3200. Support flange 3120 may be relatively thicker than thesealing flange. The support flange 3120 is disposed between the sealingflange and the marginal edge of the plenum chamber 3200, and extends atleast part of the way around the perimeter. The support flange is orincludes a spring-like element and functions to support the sealingflange from buckling in use. In use the sealing flange can readilyrespond to system pressure in the plenum chamber 3200 acting on itsunderside to urge it into tight sealing engagement with the face.

In one form the seal-forming portion of the non-invasive patientinterface 3000 comprises a pair of nasal puffs, or nasal pillows, eachnasal puff or nasal pillow being constructed and arranged to form a sealwith a respective naris of the nose of a patient.

Nasal pillows in accordance with an aspect of the present technologyinclude: a frusto-cone, at least a portion of which forms a seal on anunderside of the patient's nose, a stalk, a flexible region on theunderside of the frusto-cone and connecting the frusto-cone to thestalk. In addition, the structure to which the nasal pillow of thepresent technology is connected includes a flexible region adjacent thebase of the stalk. The flexible regions can act in concert to facilitatea universal joint structure that is accommodating of relative movementboth displacement and angular of the frusto-cone and the structure towhich the nasal pillow is connected. For example, the frusto-cone may beaxially displaced towards the structure to which the stalk is connected.

In one form, the non-invasive patient interface 3000 comprises aseal-forming portion that forms a seal in use on an upper lip region(that is, the lip superior) of the patient's face.

In one form the non-invasive patient interface 3000 comprises aseal-forming portion that forms a seal in use on a chin-region of thepatient's face.

5.3.2 Plenum Chamber

The plenum chamber 3200 has a perimeter that is shaped to becomplementary to the surface contour of the face of an average person inthe region where a seal will form in use. In use, a marginal edge of theplenum chamber 3200 is positioned in close proximity to an adjacentsurface of the face. Actual contact with the face is provided by theseal-forming structure 3100. The seal-forming structure 3100 may extendin use about the entire perimeter of the plenum chamber 3200.

5.3.3 Positioning and Stabilising Structure

The seal-forming portion 3100 of the patient interface 3000 of thepresent technology may be held in sealing position in use by thepositioning and stabilising structure 3300.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided that is configured in a manner consistentwith being worn by a patient while sleeping. In one example thepositioning and stabilising structure 3300 has a low profile, orcross-sectional thickness, to reduce the perceived or actual bulk of theapparatus. In one example, the positioning and stabilising structure3300 comprises at least one strap having a rectangular cross-section. Inone example the positioning and stabilising structure 3300 comprises atleast one flat strap.

In one form of the present technology, a positioning and stabilisingstructure 3300 comprises a strap constructed from a laminate of a fabricpatient-contacting layer, a foam inner layer and a fabric outer layer.In one form, the foam is porous to allow moisture, (e.g., sweat), topass through the strap. In one form, the fabric outer layer comprisesloop material to engage with a hook material portion.

In certain forms of the present technology, a positioning andstabilising structure 3300 comprises a strap that is extensible, e.g.resiliently extensible. For example the strap may be configured in useto be in tension, and to direct a force to draw a cushion into sealingcontact with a portion of a patient's face. In an example the strap maybe configured as a tie.

In certain forms of the present technology, a positioning andstabilising structure 3300 comprises a strap that is bendable and e.g.non-rigid. An advantage of this aspect is that the strap is morecomfortable for a patient to lie upon while the patient is sleeping.

5.3.4 Vent

In one form, the patient interface 3000 includes a vent 3400 constructedand arranged to allow for the washout of exhaled gases, e.g. carbondioxide.

One form of vent 3400 in accordance with the present technologycomprises a plurality of holes, for example, about 20 to about 80 holes,or about 40 to about 60 holes, or about 45 to about 55 holes.

The vent 3400 may be located in the plenum chamber 3200. Alternatively,the vent 3400 is located in a decoupling structure 3500, e.g., a swivel3510.

In another form in accordance with the present technology, the vent 3400may comprise a first side 3410 and a second side 3430. The first side3410 may comprise a plurality of first openings 3415. The first openings3415 may be uniform in at least one of size and shape across the firstside 3410. Each first opening 3415 extends from the first side 3410towards the second side 3430 and terminate at a plane or an interface oran interface region 3440. The second side 3430 comprises a plurality ofsecond openings 3435. The second openings 3435 may be uniform in atleast one of size and shape across the second side 3430. Each secondopening 3435 extends from the second side 3430 towards the first side3410 and terminate at the plane 3440. The plurality of first openings3415 may be positioned in an offset arrangement relative to the secondopenings 3435. For example, as shown in FIG. 7A, the first openings 3415on the first side 3410 may be positioned such that they only partiallyoverlap the second openings 3435 on the second side 3430. Each firstopening 3415 may partially overlap at least one second opening 3435along the plane 3440 to form a vent passage (e.g. a constricted passage3420) therebetween, as shown in FIG. 7E. The plane 3440 may be a plane3440 that runs in between the first 3410 and second sides 3430 andthrough the plurality of constricted passages 3420. The constrictedpassages 3420 may define the flow path 3450 for the flow of gas throughthe vent 3400. The plane 3440 may run horizontally between the firstside 3410 and the second side 3430. The plane 3440 may also be curved,as shown in FIG. 7G. The first side 3410 may be substantially parallelto the second side 3430. Alternatively, the first side 3410 may and/orsecond side 3430 may comprise uneven surfaces that are non-parallel toeach other.

The first openings 3415 may each be formed by a first wall 3418 thatsurrounds each first opening 3415. The first wall 3418 may be formed bya single curved surface that forms a single side 3421. Alternatively,the first wall 3418 may comprise a plurality of discrete sides 3421. Forexample, each first opening 3415 may comprise a plurality of sides 3421to form a substantially cuboid shaped first opening 3415. Alternatively,the first openings may be formed by a single curved surface comprising asingle side to form a substantially cylindrical shape such that thefirst opening 3415 is substantially circular in cross-section. Othershapes of the first openings 3415 may be formed to direct the desiredflow characteristics of the flow of gas through the first openings 3415.For example, the first openings 3415 may be trapezoidal or triangularprism in shape or the first openings 3415 may have any other polygonalprofile. Furthermore, the second openings 3435 may also be shaped in anyof the ways described above for the first openings 3415. Additionally,the first openings 3415 and the second openings 3435 may be shapeddifferently from one another. The shape of each opening may be modifiedto provide the desired flow characteristics to achieve one or more of: anoise reduction, an increased diffuseness or a reduction in ventblockage under humidification.

The first walls 3418 forming the plurality of first openings 3415 maycomprise an angled, tilted or curved side shape to direct the flow ofgas through the opening in a predetermined orientation to decreasenoise, increase diffuseness and/or decrease blockage underhumidification. For example, the first walls 3418 may direct the flow ofbreathable gas along a surface of the first wall 3418 and through thefirst openings 3415, in a direction to diffuse the overall flow of gasexiting the vent 3400. Alternatively, the first walls 3418 may form atortuous or crossover flow path to decrease noise and increasediffuseness. In one form of the present technology, the first openingdepth 3419 may be 0.3 mm and the 3417 width and height 3416 of the firstopening 3415 may be 0.5 mm. In another form, the first openings 3415 maybe formed by a plurality of walls.

The second openings 3435 may each be formed by a second wall 3438 thatsurrounds each second opening 3435. The second wall 3438 may be formedby a single curved surface that forms a single side 3421. Alternatively,the second wall 3438 may comprise a plurality of discrete sides 3421.For example, each second opening 3435 may comprise a plurality of sides3421 to form a substantially cuboid shaped second opening 3435.Alternatively, the second openings 3435 may be formed by a single curvedsurface comprising a single side 3421 to form a substantiallycylindrical shape such that the second opening 3435 is substantiallycircular in cross-section. Other shapes of the second openings 3435 maybe formed to direct the desired flow characteristics of the flow of gasthrough the second openings 3435. For example, the second openings 3435may be trapezoidal or triangular prism in shape or the second openings3435 may have any other polygonal profile. For example, the second walls3438 may direct the flow of gas flowing through the second openings3435, in a direction to diffuse the overall flow through the openings.Alternatively, the second walls 3438 may form a tortuous or crossoverflow path to decrease noise and increase diffuseness. In another form ofthe present technology, the first openings 3415 may be angled relativeto the second openings 3435 to direct the flow of gas through the ventin a predetermined orientation to diffuse the flow and reduce vent 3400noise.

For example, the sides 3421 of each first wall 3418 in FIG. 7K aretilted toward one another such that each first opening 3415 increases incross-sectional area away from the plane 3440. For example, the sides3421 of each first wall 3418 may be tilted at an oblique (e.g., obtuseor acute) angle relative to the interface 3440. In other words, eachfirst wall 3418 is thinner further from the interface 3440, while eachfirst opening 3415 is wider. Similarly, the sides 3421 of each secondwall 3438 are tilted toward one another such that each second opening3435 increases in cross-sectional area away from the plane 3440. Forexample, the sides 3421 of each second wall 3438 may be tilted at anobtuse angle relative to the interface 3440. In other words, each secondwall 3438 is thinner further from the interface 3440, while each secondopening 3435 is wider. Thus, this arrangement provides a flow path 3450through the constricted passages that is generally straight.

In one form of the present technology, the second opening depth 3439 maybe 0.3 mm or about 0.3 mm and the width and the height of the secondopening 3435 may each be 0.5 mm or about 0.5 mm. Each first opening 3415may partially overlap a plurality of second openings 3435, while eachsecond opening 3435 may simultaneously partially overlap a plurality offirst openings 3415. For example, as depicted in FIG. 7H, each firstopening 3415 may partially overlap four second openings 3435, while eachsecond opening 3435 simultaneously partially overlaps four of the firstopenings 3415. In another form, the second openings 3435 may be formedby a plurality of walls 3438.

As illustrated in FIG. 7E and 7H. Each first opening 3415 may at leastpartially overlap at least one second opening 3435 along the plane 3440to form a constricted passage 3420 with a width and height ofapproximately 0.1 mm to approximately 0.15 mm. The first wall 3418extends from the first side 3410 and terminate at the plane 3440 whilethe second wall 3438 extends from the second side 3430 and terminates atthe plane 3440 on an opposing side to the first wall 3418. The firstwall 3418 does not directly oppose the second wall 3438 therebypreventing water droplets from collecting therebetween to cause blockageunder humidification. For example, the sloped sides in FIG. 7E allow anymoisture that may condense on the vent 3400 to flow through theconstricted passage.

In another form, the vent passage may be formed by a wall extending fromthe first side 3410 to the second side 3430. The wall forms the firstopening 3415 extending from the first side 3410 and transitions towardsthe second side 3430 to form the second opening 3435, wherein the wallforms a stepped cross section to form the constricted passage 3420between the first 3415 and second openings 3435.

In one form of the present technology shown in FIG. 7L, the first wall3418 of each first opening 3415 may be angled relative to the secondwall 3438 of the second opening 3435 such that the flow of breathablegas passing is directed to an angled flow path through the vent 3400. Inthe example shown in FIG. 7L, the sides 3421 of each first wall 3418 aretilted in substantially the same direction relative to the plane 3440.For example, one of the sides 3421 of the first wall 3418 is tiltedrelative to the interface 3440 at an obtuse angle and another one of thesides 3421 of the first wall 3418 is tilted relative to the interface3440 at an acute angle. However, the sides 3421 of each second wall 3438are tilted towards one another. For example, the sides 3421 of eachsecond wall 3438 may be tilted relative to the interface 3440 at anobtuse angle. This arrangement results in differently shaped flow paths3450 through the constricted passages 3420 such that one flow path 3450follows a more tortuous or non-linear path, while an adjacent flow path3450 is generally straight. Furthermore, such an arrangement may promoteincreased cross-flow of the flow paths 3450 to promote diffusion.

In another example of the present technology as illustrated in FIG. 7M,the first wall 3418 may be angled relative to the second wall 3438 suchthat the flow of gas flowing from the second opening 3435 and into thefirst opening 3415 may crossover the flow path of gas flowing from anadjacent second opening into the same first opening. In the exampleshown in FIG. 7M, the sides 3421 of each first wall 3418 are tilted insubstantially the same direction relative to the plane 3440 and thesides 3421 of each second wall 3438 are also tilted in substantially thesame direction relative to the plane 3440. For example, one of the sides3421 of the first wall 3418 is tilted relative to the interface 3440 atan obtuse angle and another one of the sides 3421 of the first wall 3418is tilted relative to the interface 3440 at an acute angle. For example,one of the sides 3421 of the second wall 3438 is tilted relative to theinterface 3440 at an obtuse angle and another one of the sides 3421 ofthe second wall 3438 is tilted relative to the interface 3440 at anacute angle. However, the sides 3421 of each first wall 3418 and thesides 3421 of each second wall 3438 are tilted in opposite directionsrelative to one another. This arrangement may result in each flow path3450 through each constricted passage 3420 being non-linear or tortuous.Furthermore, such an arrangement may promote increased cross-flow of theflow paths 3450 to promote diffusion.

Additional, exemplary arrangements of the vent 3400 according to thepresent technology are shown in FIG. 9A-9C.

In FIG. 9A, the first wall 3418 has one side 3421 that is tilted towardthe second wall 3438 relative to the plane 3440 and another side 3421that is substantially perpendicular to the plane 3440. The second wall3418 also has one side 3421 that is tilted toward the first wall 3418relative to the plane 3440 and another side 3421 that is substantiallyperpendicular to the plane 3440. The side 3421 of each respective wall3418, 3438 that is tilted toward the other wall is located on oppositesides of the constricted passage 3420. As shown, this arrangementpromotes cross-flow between the flow paths 3450.

In FIG. 9B, the first wall 3418 has one side 3421 that is tilted towardthe second wall 3438 relative to the plane 3440 and another side 3421that is substantially perpendicular to the plane 3440. The second wall3418 has two sides 3421 that are both substantially perpendicular to theplane 3440. As shown, this arrangement promotes cross-flow between theflow paths 3450.

In FIG. 9C, the sides 3421 of the first wall 3418 and the second wall3438 are substantially perpendicular to the plane 3440. There is also athird wall 3428 that has sides 3421 that are substantially perpendicularto the plane 3440. Also, the third wall 3428 is positioned between thefirst wall 3418 and the second wall 3438. Furthermore, the third wall3428 is narrower than the first opening 3415 and the second wall 3438 toproduce a staggered or stepped profile through the second opening 3435.As shown, this arrangement promotes cross-flow between the flow paths3450.

In another form of the present technology, the vent may comprise aplurality of layers as shown in FIG. 8A. In some forms, the vent mayinclude 3 or more layers, each spaced apart to form a plurality ofconstricted passages 3422 between adjacent layers. The vent may beformed by a first layer 3413 and a second layer 3414. Each layer maycomprise a first side 3410 and a second side 3430. The first layer 3413may be removably or permanently attached to the second layer 3414. Thefirst side 3410 may comprise a plurality of first openings 3415, thefirst openings may have a width 3417 of approximately 0.5 mm. Similarly,the second side 3430 may comprise a plurality of second openings 3435,which may also have a width 3417 of approximately 0.5 mm. The firstopenings 3415 may partially overlap the second openings 3435 at theplane 3440 to form the constricted passage 3420. As shown in FIG. 8I,the plane 3440 may be curved to correspond to the curvature of thepatient interface 3000, such as the curvature of the plenum chamber3200, in which the vent 3400 is positioned. The plane 3440 may be curvedin a plurality of directions, such as along two orthogonal directions,for example according to curvatures of a plenum chamber 3200. The wallsof one or both of the first layer 3413 and the second layer 3414 formingthe first openings 3415 and second openings 3435 may be curved asdepicted in FIGS. 8E to 8J, or comprise curved portions. As illustrated,the first openings 3415 have a reducing cross-sectional area such thatthey converge towards the constricted passage 3422. Similarly, thesecond openings 3435 also converge towards the constricted passage 3422.As shown in FIGS. 8F and 8J, the first layer 3413 may also be spacedapart from the second layer 3414 to provide an additional constrictedpassage 3422 between the layers. The additional constriction enhancesnoise reduction and increases diffuseness of the vent 3400.

As depicted in FIG. 10, the vent 3400 may be positioned on the plenumchamber 3200 of the patient interface 3000. The first side 3410 of thevent may face the external environment of the patient interface 3000,while the second side 3430 may face the internal chamber or plenumchamber 3200 of the patient interface 3000. The vent 3400 may bepositioned such that when in use the exhaled gases of the patient flowinto the second openings 3435 on the second side 3430 of the vent,through the constricted passages 3420 and pass through the firstopenings 3415 to exit the vent. The constricted passages provide a meansof increasing the diffuseness of the flow and reducing vent noisewithout being vulnerable to vent blockage by water drops collecting inthe vent holes under humidification. Moreover, the wall or walls formingthe first openings 3415 and second openings 3435 may also be structuredto enhance desired flow characteristics of the exhaled gas flow toincrease diffuseness and decrease noise by directing the flow into adesired orientation.

In another form of the present technology, the vent 3400 may bepositioned on a connector such as an elbow or swivel connector thatconnects the patient interface 3000 to an air delivery tube or conduit.Alternatively, the vent 3400 may be positioned on the air delivery tubeor conduit.

5.3.5 Vent Manufacturing

In one form in accordance with the present technology, the vent 3400 maybe manufactured by moulding the vent 3400 using a moulding toolcomprising a tool first side 3460 and a tool second side 3470. The toolfirst side 3460 may comprise a plurality of first pins 3465 and the toolsecond side 3470 may comprise a plurality of second pins 3475. Theplurality of first pins 3465 and the plurality of second pins may bemoveable towards each other until they engage along the plane 3440. Thefirst pins 3465 may only partially overlap the second pins 3475 alongthe plane 3440. Moulding material may be added to the tool and setaround the pins such that the first openings 3415 and second openings3435 are formed around their respective first pins 3465 and second pins3475. The constricted passages 3420 may be formed around the locationsof pin partial overlap 3480 such that the plane 3440 runs through theconstricted passages 3420. The first pins 3465 and the second pins 3475may retract away from each other to demould the vent 3400 once themoulding material is set within the tool. Alternatively, either of thefirst pins 3465 or the second pins 3475 may retract such that the vent3400 may be demoulded from the remaining pins. The thickness and lengthof the first pins 3465 and second pins 3475 may be modified to form therespective first openings 3415 and second openings 3435 of apredetermined shape and size. The pins may have a thickness ofapproximately 0.3 to approximately 1 mm, or approximately 0.5 mm toprevent breakage or deformation under use. The total surface area of thepin partial overlap 3480 may be adjusted to form a constricted passage3420 having a predetermined cross sectional area. The total surface areaof the pin partial overlap 3480 may be approximately 0.05 toapproximately 0.2 mm², or approximately 0.1 mm².

FIGS. 11D and 11E depict the moulding process. FIG. 11D shows the firstside 3460 of the tool having the first pins 3465 joined to a first base3466 and the first pins 3465 define a first void 3467. The second side3470 of the tool also has the second pins 3475 joined to a second base3476 and the second pins 3475 define second voids 3477. FIG. 12E showsthe first void 3467 and the second void 3477 filled in with the materialof the vent 3400 to form the first wall 3418 and the second wall 3438,respectively. When the tool is removed from the vent 3400, may be thevent 3400 depicted in FIG. 7A, for example.

It should be understood that the manufacturing process depicted in FIGS.11A-11E could be extrapolated to produce a vent 3400 of sufficient sizefor use in a patient interface 3000. In other words, the tool to producethe vent 3400 would include many first pins 3465 and second pins 3475 toproduce a vent 3400 with many first openings 3415 and second openings3435. Furthermore, the number and size of the openings produced by thepins may be selected to yield predetermined flow characteristics. Thismethod of manufacturing also allows for each vent 3400 to be producedsubstantially identically as compared to a woven vent, for example, thatmay have blockages and other variabilities due to the fibers of theweave pattern. Additionally, this method of manufacturing the vent 3400allows for precise control of the size, number, and shape of theopenings and, therefore, the flow characteristics of the vent. Theseimprovements over a mesh or woven vent are also possible whilemaintaining substantially the same diffuseness as a mesh or woven ventand substantially the same level of noise reduction.

An alternative method of manufacturing the vent 3400 may include moldingeach wall 3418, 3438 separately and then securing the separate wallstogether. The examples show in FIGS. 8A and 8B may also be manufacturedin such a manner.

Alternatively, the vent 3400 may be formed by drilling, milling or lasercutting the first openings 3415 and/or second openings 3435 to thepredetermined cross sectional area, such that the first openings 3415only partially overlap the second openings 3435 to from a constrictedpassage 3420 therebetween. In this alternative manufacturing method, thevent 3400 may begin as a solid piece of material and then drilling,milling or laser cutting produces the first openings 3415 and/or secondopenings 3435. Additionally, or alternatively, the vent 3400 may beformed by an additive method, such as three-dimensional printing.

5.3.6 Decoupling Structure(s)

In one form the patient interface 3000 includes at least one decouplingstructure 3500, for example, a swivel 3510 or a ball and socket 3520.

5.3.7 Connection Port

Connection port 3600 allows for connection to the air circuit 4170.

5.3.8 Forehead Support

In one form, the patient interface 3000 includes a forehead support3700.

5.3.9 Anti-Asphyxia Valve

In one form, the patient interface 3000 includes an anti-asphyxia valve3800.

5.3.10 Ports

In one form of the present technology, a patient interface 3000 includesone or more ports that allow access to the volume within the plenumchamber 3200. In one form this allows a clinician to supply supplementaloxygen. In one form, this allows for the direct measurement of aproperty of gases within the plenum chamber 3200, such as the pressure.

5.4 RPT Device

An RPT device 4000 in accordance with one aspect of the presenttechnology comprises mechanical and pneumatic components 4100,electrical components 4200 and is configured to execute one or morealgorithms 4300. The RPT device may have an external housing 4010,formed in two parts, an upper portion 4012 and a lower portion 4014.Furthermore, the external housing 4010 may include one or more panel(s)4015. The RPT device 4000 comprises a chassis 4016 that supports one ormore internal components of the RPT device 4000. The RPT device 4000 mayinclude a handle 4018.

The pneumatic path of the RPT device 4000 may comprise one or more airpath items, e.g., an inlet air filter 4112, an inlet muffler 4122, apressure generator 4140 capable of supplying air at positive pressure(e.g., a blower 4142), an outlet muffler 4124 and one or moretransducers 4270, such as pressure sensors 4272 and flow rate sensors4274.

One or more of the air path items may be located within a removableunitary structure which will be referred to as a pneumatic block 4020.The pneumatic block 4020 may be located within the external housing4010. In one form a pneumatic block 4020 is supported by, or formed aspart of the chassis 4016.

The RPT device 4000 may have an electrical power supply 4210, one ormore input devices 4220, a central controller 4230, a therapy devicecontroller 4240, a pressure generator 4140, one or more protectioncircuits 4250, memory 4260, transducers 4270, data communicationinterface 4280 and one or more output devices 4290. Electricalcomponents 4200 may be mounted on a single Printed Circuit BoardAssembly (PCBA) 4202. In an alternative form, the RPT device 4000 mayinclude more than one PCBA 4202.

5.4.1 Air Circuit

An air circuit 4170 in accordance with an aspect of the presenttechnology is a conduit or a tube constructed and arranged in use toallow a flow of air to travel between two components such as thepneumatic block 4020 and the patient interface 3000.

In particular, the air circuit 4170 may be in fluid connection with theoutlet of the pneumatic block and the patient interface. The air circuitmay be referred to as an air delivery tube. In some cases there may beseparate limbs of the circuit for inhalation and exhalation. In othercases a single limb is used.

In some forms, the air circuit 4170 may comprise one or more heatingelements configured to heat air in the air circuit, for example tomaintain or raise the temperature of the air. The heating element may bein a form of a heated wire circuit, and may comprise one or moretransducers, such as temperature sensors. In one form, the heated wirecircuit may be helically wound around the axis of the air circuit 4170.The heating element may be in communication with a controller such as acentral controller 4230 or a humidifier controller 5250. One example ofan air circuit 4170 comprising a heated wire circuit is described inUnited States Patent Application No. US/2011/0023874, which isincorporated herewithin in its entirety by reference.

5.5 Humidifier 5.5.1 Humidifier Overview

In one form of the present technology there is provided a humidifier5000 (e.g. as shown in FIG. 5A) to change the absolute humidity of airor gas for delivery to a patient relative to ambient air. Typically, thehumidifier 5000 is used to increase the absolute humidity and increasethe temperature of the flow of air (relative to ambient air) beforedelivery to the patient's airways.

The humidifier 5000 may comprise a humidifier reservoir 5110, ahumidifier inlet 5002 to receive a flow of air, and a humidifier outlet5004 to deliver a humidified flow of air. In some forms, as shown inFIG. 5A and FIG. 5B, an inlet and an outlet of the humidifier reservoir5110 may be the humidifier inlet 5002 and the humidifier outlet 5004respectively. The humidifier 5000 may further comprise a humidifier base5006, which may be adapted to receive the humidifier reservoir 5110 andcomprise a heating element 5240.

5.6 Breathing Waveforms

FIG. 6A shows a model typical breath waveform of a person whilesleeping. The horizontal axis is time, and the vertical axis isrespiratory flow rate. While the parameter values may vary, a typicalbreath may have the following approximate values: tidal volume, Vt, 0.5L, inhalation time, Ti, 1.6 s, peak inspiratory flow rate, Qpeak, 0.4L/s, exhalation time, Te, 2.4 s, peak expiratory flow rate, Qpeak, −0.5L/s. The total duration of the breath, Ttot, is about 4 s. The persontypically breathes at a rate of about 15 breaths per minute (BPM), withVentilation, Vent, about 7.5 L/minute. A typical duty cycle, the ratioof Ti to Ttot is about 40%.

5.7 Glossary

For the purposes of the present technology disclosure, in certain formsof the present technology, one or more of the following definitions mayapply. In other forms of the present technology, alternative definitionsmay apply.

5.7.1 General

Air: In certain forms of the present technology, air may be taken tomean atmospheric air, and in other forms of the present technology airmay be taken to mean some other combination of breathable gases, e.g.atmospheric air enriched with oxygen.

Ambient: In certain forms of the present technology, the term ambientwill be taken to mean (i) external of the treatment system or patient,and (ii) immediately surrounding the treatment system or patient.

For example, ambient humidity with respect to a humidifier may be thehumidity of air immediately surrounding the humidifier, e.g. thehumidity in the room where a patient is sleeping. Such ambient humiditymay be different to the humidity outside the room where a patient issleeping.

In another example, ambient pressure may be the pressure immediatelysurrounding or external to the body.

In certain forms, ambient (e.g., acoustic) noise may be considered to bethe background noise level in the room where a patient is located, otherthan for example, noise generated by an RPT device or emanating from amask or patient interface. Ambient noise may be generated by sourcesoutside the room.

Respiratory Pressure Therapy (RPT): The application of a supply of airto an entrance to the airways at a treatment pressure that iscontinuously positive with respect to atmosphere.

Continuous Positive Airway Pressure (CPAP) therapy: Respiratory pressuretherapy in which the treatment pressure is approximately constantthrough a respiratory cycle of a patient. In some forms, the pressure atthe entrance to the airways will be slightly higher during exhalation,and slightly lower during inhalation. In some forms, the pressure willvary between different respiratory cycles of the patient, for example,being increased in response to detection of indications of partial upperairway obstruction, and decreased in the absence of indications ofpartial upper airway obstruction.

Patient: A person, whether or not they are suffering from a respiratorydisease.

Automatic Positive Airway Pressure (APAP) therapy: CPAP therapy in whichthe treatment pressure is continuously adjustable, e.g. from breath tobreath, between minimum and maximum limits, depending on the presence orabsence of indications of SDB events.

5.7.2 RPT Device Parameters

Flow rate: The instantaneous volume (or mass) of air delivered per unittime. While flow rate and ventilation have the same dimensions of volumeor mass per unit time, flow rate is measured over a much shorter periodof time. In some cases, a reference to flow rate will be a reference toa scalar quantity, namely a quantity having magnitude only. In othercases, a reference to flow rate will be a reference to a vectorquantity, namely a quantity having both magnitude and direction. Whereit is referred to as a signed quantity, a flow rate may be nominallypositive for the inspiratory portion of a breathing cycle of a patient,and hence negative for the expiratory portion of the breathing cycle ofa patient. Flow rate may be given the symbol Q. ‘Flow rate’ is sometimesshortened to simply ‘flow’.

Leak: The word leak will be taken to be an unintended flow of air. Inone example, leak may occur as the result of an incomplete seal betweena mask and a patient's face. In another example leak may occur in aswivel elbow to the ambient.

Noise, conducted (acoustic): Conducted noise in the present documentrefers to noise which is carried to the patient by the pneumatic path,such as the air circuit and the patient interface as well as the airtherein. In one form, conducted noise may be quantified by measuringsound pressure levels at the end of an air circuit.

Noise, radiated (acoustic): Radiated noise in the present documentrefers to noise which is carried to the patient by the ambient air. Inone form, radiated noise may be quantified by measuring soundpower/pressure levels of the object in question according to ISO 3744.

Noise, vent (acoustic): Vent noise in the present document refers tonoise which is generated by the flow of air through any vents such asvent holes in the patient interface.

Sound Power: The energy per unit time carried by a sound wave. The soundpower is proportional to the square of sound pressure multiplied by thearea of the wavefront. Sound power is usually given in decibels SWL,that is, decibels relative to a reference power, normally taken as 10⁻¹²watt.

Sound Pressure: The local deviation from ambient pressure at a giventime instant as a result of a sound wave travelling through a medium.Sound pressure is usually given in decibels SPL, that is, decibelsrelative to a reference pressure, normally taken as 20×10⁻⁶ Pascal (Pa),considered the threshold of human hearing.

5.7.3 Materials

Silicone or Silicone Elastomer: A synthetic rubber. In thisspecification, a reference to silicone is a reference to liquid siliconerubber (LSR) or a compression moulded silicone rubber (CMSR). One formof commercially available LSR is SILASTIC (included in the range ofproducts sold under this trademark), manufactured by Dow Corning.Another manufacturer of LSR is Wacker. Unless otherwise specified to thecontrary, an exemplary form of LSR has a Shore A (or Type A) indentationhardness in the range of about 35 to about 45 as measured using ASTMD2240 (year?required??)

Polycarbonate: a typically transparent thermoplastic polymer ofBisphenol-A Carbonate.

5.7.4 Aspects of a Patient Interface

Anti-asphyxia valve (AAV): The component or sub-assembly of a masksystem that, by opening to atmosphere in a failsafe manner, reduces therisk of excessive CO₂ rebreathing by a patient.

Elbow: A conduit that directs an axis of flow of air to change directionthrough an angle. In one form, the angle may be approximately 90degrees. In another form, the angle may be less than 90 degrees. Theconduit may have an approximately circular cross-section. In anotherform the conduit may have an oval or a rectangular cross-section.

Frame: Frame will be taken to mean a mask structure that bears the loadof tension between two or more points of connection with a headgear. Amask frame may be a non-airtight load bearing structure in the mask.However, some forms of mask frame may also be air-tight.

Headgear: Headgear will be taken to mean a form of positioning andstabilizing structure designed for use on a head. Preferably theheadgear comprises a collection of one or more struts, ties andstiffeners configured to locate and retain a patient interface inposition on a patient's face for delivery of respiratory therapy. Someties are formed of a soft, flexible, elastic material such as alaminated composite of foam and fabric.

Membrane: Membrane will be taken to mean a typically thin element thathas, preferably, substantially no resistance to bending, but hasresistance to being stretched.

Plenum chamber: a mask plenum chamber will be taken to mean a portion ofa patient interface having walls at least partially enclosing a volumeof space, the volume having air therein pressurised above atmosphericpressure in use. A shell may form part of the walls of a mask plenumchamber.

Seal: The noun form (“a seal”) will be taken to mean a structure orbarrier that intentionally resists the flow of air through the interfaceof two surfaces. The verb form (“to seal”) will be taken to mean toresist a flow of air.

Shell: A shell will be taken to mean a curved, relatively thin structurehaving bending, tensile and compressive stiffness. For example, a curvedstructural wall of a mask may be a shell. In some forms, a shell may befaceted. In some forms a shell may be airtight. In some forms a shellmay not be airtight.

Stiffener: A stiffener will be taken to mean a structural componentdesigned to increase the bending resistance of another component in atleast one direction.

Strut: A strut will be taken to be a structural component designed toincrease the compression resistance of another component in at least onedirection.

Swivel: (noun) A subassembly of components configured to rotate about acommon axis, preferably independently, preferably under low torque. Inone form, the swivel may be constructed to rotate through an angle of atleast 360 degrees. In another form, the swivel may be constructed torotate through an angle less than 360 degrees. When used in the contextof an air delivery conduit, the sub-assembly of components preferablycomprises a matched pair of cylindrical conduits. There may be little orno leak flow of air from the swivel in use.

Tie: A tie will be taken to be a structural component designed to resisttension.

Vent: (noun) the structure that allows a flow of air from an interior ofthe mask, or conduit, to ambient air to allow clinically effectivewashout of exhaled gases. For example, a clinically effective washoutmay involve a flow rate of about 10 litres per minute to about 100litres per minute, depending on the mask design and treatment pressure.

5.7.5 Terms Used in Relation to Patient Interface

Curvature (of a surface): A region of a surface having a saddle shape,which curves up in one direction and curves down in a differentdirection, will be said to have a negative curvature. A region of asurface having a dome shape, which curves the same way in two principaldirections, will be said to have a positive curvature. A flat surfacewill be taken to have zero curvature.

Floppy: A quality of a material, structure or composite that is one ormore of:

-   -   Readily conforming to finger pressure.    -   Unable to retain its shape when caused to support its own        weight.    -   Not rigid.    -   Able to be stretched or bent elastically with little effort.

The quality of being floppy may have an associated direction, hence aparticular material, structure or composite may be floppy in a firstdirection, but stiff or rigid in a second direction, for example asecond direction that is orthogonal to the first direction.

Resilient: Able to deform substantially elastically, and to releasesubstantially all of the energy upon unloading, within a relativelyshort period of time such as 1 second.

Rigid: Not readily deforming to finger pressure, and/or the tensions orloads typically encountered when setting up and maintaining a patientinterface in sealing relationship with an entrance to a patient'sairways.

Semi-rigid: means being sufficiently rigid to not substantially distortunder the effects of mechanical forces typically applied duringrespiratory pressure therapy.

5.8 Other Remarks

Unless the context clearly dictates otherwise and where a range ofvalues is provided, it is understood that each intervening value, to thetenth of the unit of the lower limit, between the upper and lower limitof that range, and any other stated or intervening value in that statedrange is encompassed within the technology. The upper and lower limitsof these intervening ranges, which may be independently included in theintervening ranges, are also encompassed within the technology, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the technology.

Furthermore, where a value or values are stated herein as beingimplemented as part of the technology, it is understood that such valuesmay be approximated, unless otherwise stated, and such values may beutilized to any suitable significant digit to the extent that apractical technical implementation may permit or require it.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this technology belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present technology, a limitednumber of the exemplary methods and materials are described herein.

When a particular material is identified as being used to construct acomponent, obvious alternative materials with similar properties may beused as a substitute. Furthermore, unless specified to the contrary, anyand all components herein described are understood to be capable ofbeing manufactured and, as such, may be manufactured together orseparately.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include their plural equivalents,unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated herein by referencein their entirety to disclose and describe the methods and/or materialswhich are the subject of those publications. The publications discussedherein are provided solely for their disclosure prior to the filing dateof the present application. Nothing herein is to be construed as anadmission that the present technology is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dates,which may need to be independently confirmed.

The terms “comprises” and “comprising” should be interpreted asreferring to elements, components, or steps in a non-exclusive manner,indicating that the referenced elements, components, or steps may bepresent, or utilized, or combined with other elements, components, orsteps that are not expressly referenced.

The subject headings used in the detailed description are included onlyfor the ease of reference of the reader and should not be used to limitthe subject matter found throughout the disclosure or the claims. Thesubject headings should not be used in construing the scope of theclaims or the claim limitations.

Although the technology herein has been described with reference toparticular examples, it is to be understood that these examples aremerely illustrative of the principles and applications of thetechnology. In some instances, the terminology and symbols may implyspecific details that are not required to practice the technology. Forexample, although the terms “first” and “second” may be used, unlessotherwise specified, they are not intended to indicate any order but maybe utilised to distinguish between distinct elements. Furthermore,although process steps in the methodologies may be described orillustrated in an order, such an ordering is not required. Those skilledin the art will recognize that such ordering may be modified and/oraspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be madeto the illustrative examples and that other arrangements may be devisedwithout departing from the spirit and scope of the technology.

5.9 Reference Signs List

Part References Numbers patient 1000 bed partner 1100 patient interface3000 seal-forming structure 3100 plenum chamber 3200 position andstabilising structure 3300 vent 3400 first side 3410 first layer 3413second layer 3414 first opening 3415 first opening height 3416 firstopening height width 3417 first wall 3418 first opening depth 3419constricted passage 3420 side 3421 constricted passage 3422 second side3430 second opening 3435 second wall 3438 second opening depth 3439plane 3440 tool first side 3460 first pins 3465 first base 3466 firstvoid 3467 tool second side 3470 second pins 3475 second base 3476 secondvoid 3477 pin partial overlap 3480 decoupling structure 3500 onedecoupling structure 3500 swivel 3510 socket 3520 connection port 3600forehead support 3700 anti-asphyxia valve 3800 rpt device 4000 externalhousing 4010 upper portion 4012 lower portion 4014 panels 4015 chassis4016 handle 4018 pneumatic block 4020 pneumatic components 4100 airfilter 4110 inlet air filter 4112 outlet air filter 4114 inlet muffler4122 outlet muffler 4124 pressure generator 4140 blower 4142 motor 4144air circuit 4170 electrical components 4200 PCBA 4202 power supply 4210input device 4220 central controller 4230 therapy device controller 4240protection circuits 4250 memory 4260 transducer 4270 pressure sensor4272 flow rate sensors 4274 data communication interface 4280 outputdevice 4290 algorithms 4300 humidifier 5000 humidifier inlet 5002humidifier outlet 5004 humidifier base 5006 reservoir 5110 conductiveportion 5120 reservoir dock 5130 locking lever 5135 water levelindicator 5150 heating element 5240

1. A gas washout vent for a patient interface, the vent configured toallow a flow of patient exhaled gas to an exterior of the patientinterface to minimise rebreathing of exhaled gas by the patient, saidvent comprising: a plurality of vent passages extending through a firstside and a second side of the vent, each vent passage comprising: aplurality of first openings extending through the first side towards thesecond side, said first openings being uniform in size and shape; aplurality of second openings extending through the second side towardsthe first side, said second openings being uniform in size and shape;and wherein the first side and the second side are fixed together suchthat the first openings and the second openings partially overlap eachother at an interface to form constricted passages therebetween.
 2. Thegas washout vent of claim 1, wherein the first openings and the secondopenings terminate at the interface to form the constricted passages. 3.The gas washout vent of claim 1, wherein the interface is curved.
 4. Thegas washout vent of claim 1, wherein the interface is flat.
 5. The gaswashout vent of claim 1, wherein each of the first openings partiallyoverlaps a plurality of the second openings.
 6. The gas washout vent ofclaim 1, wherein each of the first openings has a substantially constantcross sectional area through the first side that is larger than a crosssectional area of the constricted passage.
 7. The gas washout vent ofclaim 1, wherein each of the second openings has a substantiallyconstant cross sectional area through the second side that is largerthan a cross sectional area of the constricted passage.
 8. The gaswashout vent of claim 1, wherein each of the first openings and each ofthe second openings are formed by a curved wall.
 9. The gas washout ventof claim 8, wherein the wall forms a cylindrical opening.
 10. The gaswashout vent of claim 1, wherein at least one of the first openings andat least one of the second openings has a varying cross sectional area.11. The gas washout vent of claim 10, wherein the varying crosssectional area has a minimum cross sectional area that is larger thanthe cross sectional area of the corresponding constricted passage. 12.The gas washout vent of claim 10, wherein each of the first openings isformed by at least a first wall.
 13. The gas washout vent of claim 12,wherein the first wall comprises a plurality of first sides.
 14. The gaswashout vent of claim 13, wherein the plurality of first sides includesat least one tilted first side to form an angled flow path through eachof the first openings.
 15. The gas washout vent of claim 13, wherein theplurality of first sides includes at least one curved first side. 16.The gas washout vent of claim 12, wherein each of the second openings isformed by a second wall.
 17. The gas washout vent of claim 13, whereinthe second wall comprises a plurality of second sides.
 18. The gaswashout vent of claim 17, wherein the plurality of second sides includesat least one tilted second side to form an angled flow path though eachof the second openings.
 19. The gas washout vent according to claim 18,wherein at least one of the second sides of the second wall of one ofthe second openings is tilted relative to at least one of the secondsides of the second wall of an adjacent one of the second openings suchthat the flow of exhaled gases exiting one of the second openings isdirected towards the flow exiting the adjacent one of the secondopenings.
 20. The gas washout vent of claim 17, wherein the plurality ofsecond sides includes at least one curved second side.